Protective Effect Of Mitogen-and Stress-activated Protein Kinase (MSK) In Rats With Focal Ischemia-reperfusion Injury

Objective: To study the effect of mitogen- and stress-activated protein kinase (MSK) in rats suffered with ischemia-reperfusion injury, and further study the role and mechanism of MSK after rat cerebral ischemia-reperfusion at the cellular level.Methods: Healthy male Sprague-Dawley rats were randomly divided into 3 groups: operation group, sham operation group, and control group. The operation group was established with the cerebral ischemia reperfusion injury model by inserting thread into middle cerebral artery. The procedure to establish the sham operation group was similar to the operation group but without inserting thread into middle cerebral artery. The expression of MSK, caspase-3, and INOS in rat brain were measured by immunoblotting. The localization of MSK in rat brain was measured by immunofluorescence assay. In model of neuronal apoptosis and astrocyte inflammatory response, through over-expressing MSK and transfection of siRNA against MSK, the effects of MSK in cell apoptosis and inflammatory process were respectively studied by using the CCK-8 method and immunoblotting.Results: In the operation group, the expression of MSK was reduced at the early stage and then recovered with time going after cerebral ischemic reperfusion. MSK was found to localize in neurons and astrocytes by immunofluorescence assay. The expression changes of caspase-3 and INOS were in the opposite trend with respect to MSK. Glutamate induced the highly differentiated PC12 cells to apoptosis, depending on the concentration of glutamate and action time. Apoptosis decreased, when MSK was over-expressed; while apoptosis increased, when the expression of MSK was interfered. The expression of INOS and IL-10 were significantly increased after astrocytes were treated with LPS, which depended on the concentration of LPS and action time. Over-expressing MSK decreased the expression of INOS and increased the expression of IL-10. Interfering the expression of MSK increased the expression of INOS and decreased the expression of IL-10.Conclusions: 1. The expression changes of caspase-3 and INOS were in the opposite trend with respect to MSK, and the role of MSK is related to the biological behaviors of neurons and astrocytes. 2. MSK has an anti-apoptosis effect on neurons. 3. MSK inhibits inflammation of astrocytes.